1. Field of the Invention
This invention relates to solenoids, in general, and to latching solenoids in particular and, especially, latching solenoids which are magnetically latched.
2. Prior Art
There are many electro-magnetic devices known in the prior art. Many of these electro-magnetic devices take the form of coils of wire mounted on cores, usually of ferromagnetic material. In many cases the devices take the form of relays which move armatures relative to the core in response to an electrical signal applied to the coil.
These types of devices are often referred to as switches or relays.
In related devices, the core, per se, moves with respect to the coil and effects an action as a result of the movement of the core. These devices are normally referred to as solenoids.
In most solenoids, an electrical signal is applied to a coil which generates electro-magnetic flux in a core. The flux operates to move the core relative to the coil and to effect a work function or operation. However, in many cases the moveable core remains in the position only in response to the application of the electrical signal to the coil. The solenoid mechanism does not latch in any particular position.
In order to provide a latching arrangement in most solenoids known in the art, it is requried to provide a separate electro-mechnical latching mechanism. However, the devices known in the prior art are subject to various problems and tend to lack reliability.
Typically, a solenoid is defined as an electrically energized coil which may consist of one or more layers of winding. It is the basis of most forms of electro-magnets and is, thus, part of the operating mechanism of many operating devices. One of the simplest forms and, at the same time, widely used form of solenoid is the so-called plunger-type solenoid. In this apparatus a coil is wound on a non-magnetic form or bobbin which includes a central (axial) opening in which a magnetic plunger may move. Application of an energizing signal to the coil pulls the plunger up into the coil and, thus, operates the associated mechanism. An iron-clad solenoid is similar except for an iron case which surrounds the coil. This iron case operates on the flux and increases the magnetic pull of the plunger. Other types of solenoids use a fixed core and various types of armatures. Solenoids are widely used for operating circuit breakers, track switches, valves and many other mechanical devices.
Consequently, it is highly desirable to have a relatively simple yet highly reliable solenoid device wherein a simple latching condition can be provided.